South Australian Gulf

8 South Australian Gulf...... 2 8.5.2 Streamflow volumes...... 28 8.1 Introduction...... 2 8.5.3 Streamflow salinity...... 28 8.2 Key information...... 3 8.5.4 Flooding...... 31 8.3 Description of the region...... 4 8.5.5 Storage systems...... 31 8.3.1 Physiographic characteristics...... 6 8.5.6 Wetlands...... 31 8.3.2 Elevation...... 7 8.5.7 Hydrogeology...... 35 8.3.3 Slopes...... 8 8.5.8 Water table salinity...... 35 8.3.4 Soil types...... 9 8.5.9 Groundwater management units...... 35 8.3.5 Land use...... 11 8.5.10 Status of selected aquifers...... 39 8.3.6 Population distribution...... 13 8.6 Water for cities and towns...... 47 8.3.7 Rainfall zones...... 14 8.6.1 Urban centres...... 47 8.3.8 Rainfall deficit...... 15 8.6.2 Sources of water supply...... 49 8.4 Landscape water flows...... 16 8.6.3 Adelaide...... 49 8.4.1 Rainfall...... 17 8.7 Water for agriculture...... 55 8.4.2 Evapotranspiration...... 20 8.7.1 Soil moisture...... 55 8.4.3 Landscape water yield ...... 23 8.7.2 Irrigation water...... 56 8.5 Surface water and groundwater...... 26 8.7.3 Irrigation areas...... 56 8.5.1 Rivers...... 26 8.7.4 McLaren Vale prescribed wells area...... 56 South Australian Gulf

8 South Australian Gulf

8.1 Introduction Spatial and temporal patterns in landscape water flows are presented as well as an examination of This chapter examines water resources in the South the surface and groundwater resources. The chapter Australian Gulf region in 2011–12 and over recent concludes with a review of the water situation for decades. It starts with summary information on urban centres and irrigation areas. The data sources the status of water flows, stores and use. This is and methods used in developing the diagrams and followed by descriptive information for the region maps are listed in the Technical Supplement. including the physiographic characteristics, soil types, population, land use and climate.

2 Australian Water Resources Assessment 2012 8.2 Key information

Table 8.1 gives an overview of the key components of the data and information in this chapter.

Table 8.1 Key information on water flows, stores and use in the South Australian Gulf region

Landscape water flows Region average Difference from 1911–2012 Decile ranking with respect to the long-term annual mean 1911–2012 record Rainfall 331 mm +10% 8th­—above average Evapo- transpiration 306 mm +7% 8th­—above average Landscape water yield 9 mm – 10% 6th—average Streamflow (at selected gauges) Annual total Highly variable pattern of high and low flow in the river gauges in the south eastern flow: rivers Salinity: Annual median electrical conductivity predominantly above 1,000 μS/cm in gauges in the south eastern rivers and on Flooding: No major flooding in the monitoring gauges surrounding Adelaide

Surface water storage (comprising about 74% of the region’s total capacity of all major storages) Total 30 June 2012 30 June 2011 Change accessible accessible % of total accessible % of total accessible % of total capacity volume capacity volume capacity volume capacity 197 GL 96 GL 49% 135 GL 69% – 39 GL – 20%

Groundwater (in selected aquifers) Levels: Variable trends in the different aquifers, predominantly falling in middle aquifers and rising in deeper aquifers

Salinity: Saline groundwater (≥3,000 mg/L) throughout most of the region with non-saline (<3,000 mg/L) areas around Adelaide and in the Urban water use (Adelaide) Total sourced in 2011–12 Total sourced in Change Restrictions 2010–11 138 GL 125 GL +13 GL (+10%) Water Wise Measures

Annual mean soil moisture (model estimates) Spatial patterns: Predominantly average annual mean soil moisture and very much above average soil moisture in the far north Temporal patterns in Average to above average soil moisture throughout the year regional average:

Australian Water Resources Assessment 2012 3 South Australian Gulf

8.3 Description of the region Other significant areas of nature conservation occur on , Kangaroo Island, and The South Australian Gulf region extends over through the Mount Lofty and Flinders Ranges. 117,700 km2 of , surrounding the Gulf Irrigated agriculture is mostly for viticulture and of St Vincent and , and stretching inland wine production, the most important of which is 300 km to the north of Spencer Gulf. To the east (at concentrated in the Onkaparinga catchment. Section the border of the Murray–Darling Basin) the region is 8.7 has more information on agricultural activities in bounded by the western slopes of the Mount Lofty the region. and Flinders Ranges; to the north, it is bounded by The region has a Mediterranean climate in the the ; and to the west by the South southeast, and a semi-arid climate inland and to the Western Plateau region. The south of the region north. Rainfall mainly occurs in winter. Spring and includes Kangaroo Island. summer rainfall can be substantial although highly Except for the Flinders Ranges (with a highest peak variable. Subsections 8.3.7 and 8.3.8 provide more of 932 m) and the , the region information on the rainfall patterns and deficits across has moderately flat terrain. Subsections 8.3.1–8.3.4 the region. give more detail on the physical characteristics of There are no major permanent freshwater lakes in the region. the South Australian Gulf region. A number of large The South Australian Gulf region has a population in endorheic salt lakes exist in the north, including Lake excess of 1.4 million, or just over 6% of the country’s Torrens, Island Lagoon, Pernatty Lagoon, Lake Hart, total population (Australian Bureau of Statistics [ABS] Lake Gilles and Lake MacFarlane (Figure 8.1). In the 2011b). Major population centres in the region include south, short rivers drain into the ocean. The region Adelaide, Victor Harbour, Port Pirie, , has some important coastal and marine ecosystems. and Port Lincoln (Figure 8.1). Further The hydrogeology of the region can be partitioned discussion of the region’s population distribution and into areas of surficial and underlying sediments, urban centres can be found in subsection 8.3.6 and and areas of outcropping fractured rock. Significant section 8.6 respectively. groundwater resources are found in surficial Dryland pasture and cropping are major land uses in sediments and the Quaternary and Tertiary aquifers the region. Grazing is concentrated in the northern that underlie them. Typically fractured rock systems arid river basins such as , Willochra offer restricted low volume groundwater resources; Creek and Mambray Coast (south of Lake Torrens), however, there are some parts of this region with and the Broughton River basin. Several river basins a greater density of fractures and more substantial (Wakefield, Gawler and Broughton) have 50% or groundwater resource availability. A more detailed more of their area occupied by dryland agriculture. description of the rivers and groundwater status is More than half of the land area devoted to nature given in section 8.5. conservation is a single reserve covering the Lake Torrens salt lake (Figure 8.1).

A view of rural Southern Australia looking north towards Flinders Range | Malcolm Watson

4 Australian Water Resources Assessment 2012 Figure 8.1 Major rivers and urban centres in the South Australian Gulf region

Australian Water Resources Assessment 2012 5 South Australian Gulf

8.3.1 Physiographic characteristics southeast oriented longitudinal dunes, locally broken by granite hills, ridges of metamorphic rocks and The physiographic map in Figure 8.2 shows areas plains extending as headlands and inlets along the with similar landform evolutionary histories (Pain et southern coast. al. 2011). These can be related back to similar geology The Gulfs Ranges province occupies 57% of the and climatic impacts which define the extent of region and has a complex fold belt of prominent erosion processes. The areas have distinct physical ranges in the north, chiefly quartzite with vales characteristics that can influence hydrological on weaker rocks, and in the southeast stepped processes. The South Australian Gulf region has two fault blocks and islands, mainly of weathered physiographic provinces, namely Eyre Peninsula and metamorphic rocks with ferruginous cappings. In the Gulfs Ranges. northwest, there are dissected sandstone plateaus, The Eyre Peninsula province occupies 43% of the salt lakes, alluvial and littoral plains and stabilised region and has alluvial plains and salt lakes with longitudinal dunes. In the southwest are undulating some dunes in the north. Moving south, this changes lowlands of folded crystalline and metamorphic to rounded ranges of acid volcanic rocks and hills of rocks covered by calcrete and stabilised northwest– metamorphic rocks followed by stable northwest– southeast longitudinal dunes.

Figure 8.2 Physiographic provinces in the South Australian Gulf region

6 Australian Water Resources Assessment 2012 8.3.2 Elevation borderline on altitudes exceeding 400 m. To the north and the west of the region, the effective water divide Figure 8.3 presents ground surface elevations in is less obvious. the South Australian Gulf region. Information was The major mountains in the west are the Minbrie obtained from the Geoscience website (www.ga.gov. Range on Eyre Peninsula, which reach altitudes au/topographic-mapping/digital-elevation-data.html). of over 400 m above sea level. The western areas The region is clearly defined by the crest of the contain many closed drainage areas which do not Mount Lofty Ranges in the south and the eastern drain towards the sea. This includes the large Lake ridges of the Flinders Ranges in the north. The Torrens basin, which covers the majority of the north highest point in this area is 932 m with most of the of the region.

Figure 8.3 Ground surface elevations in the South Australian Gulf region

Australian Water Resources Assessment 2012 7 South Australian Gulf

8.3.3 Slopes Significant slopes also exist southeast of Adelaide. The slopes were derived from the elevation Areas with steep slopes provide higher run-off information used in the previous section. generating potential than flat areas. The South The region has a number of flat coastal plains, Australian Gulf region has only some areas with which, in combination with the climate and the steep slopes. Most of the area is rather flat (Table appropriate soil conditions, have formed ideal solar 8.2). The steep slopes in the map of Figure 8.4, in salt production sites. particular, highlight the Flinders Ranges in the east. The flat plains in the north are mostly salt lakes, Table 8.2 Proportions of slope classes for the region which collect the sparse run-off from their surrounding ranges. The large flat plain in the centre- Slope class (%) 0–0.5 0.5–1 1–5 > 5 north is Lake Torrens, which has only filled once Proportion of 31.4 19.8 39.8 9.0 in the last 150 years, as generally it is a large salty region (%) flatland.

Figure 8.4 Surface slopes in the South Australian Gulf region

8 Australian Water Resources Assessment 2012 8.3.4 Soil types Sodosols are common soils in the north and southwest and are scattered around in the southeast Soils play an important role in the hydrological cycle of the region. These soils have a strongly contrasting by distributing water that reaches the ground. Water texture, with impermeable sodic subsoils arising can be transported to rivers and lakes via the soil from elevated sodium concentrations and clay. They surface as run-off or enter the soil and provide water are susceptible to dryland salinity as well as erosion for plant growth as well as contribute to groundwater if vegetation is removed. recharge. The nature of these hydrological pathways Chromosols also have strongly contrasting texture, and the suitability of the soils for agricultural but have permeable subsoils which are not strongly purposes are influenced by soil types and their acidic. They are dominant in the southeast of the characteristics. Soil type information was obtained region as well as on Kangaroo Island and are mostly from the Australian Soil Resource Information present in pastures and areas used for dryland System website (www.asris.csiro.au). agriculture. About 88% of the South Australian Gulf region Tenosols are soils with minimal development consists of four soil types, namely calcarosols, throughout the profile. They show little or no change sodosols, chromosols and tenosols (Figure 8.5 and in texture and colour. They are often shallow or stony. Figure 8.6). These soils are low in chemical fertility and water- Calcarosols are widely distributed across the region holding capacity and thus their agricultural potential and cover about 45% of the total area. They are is low. Tenosols are scattered in the central-west and mainly present in areas used for pastures and to in the south of the region and are mostly present in some extent for dryland agriculture. Calcarosols are pastures and areas used for nature conservation. characterised by a high content of calcium carbonate The other soil types that have minimal representation which occurs as soft or hard white fragments or as in the South Australian Gulf region are rudosols, solid layers. These soils are often shallow and have dermosol, ferrosols, hydrosols, kurosols and a low water-holding capacity. They have a low to podosols (1–6% of the total area). moderate agricultural potential, and salinity, alkalinity and boron toxicity may often cause problems.

Figure 8.5 Soil types in the South Australian Gulf region

Australian Water Resources Assessment 2012 9 South Australian Gulf

Figure 8.6 Soil type distribution in the South Australian Gulf region

10 Australian Water Resources Assessment 2012 8.3.5 Land use More than half of the land area devoted to nature conservation is a single reserve covering the Lake Dryland pasture and cropping are major land uses Torrens salt lake. Other significant areas of nature in the region (Figure 8.7), being often combined conservation occur on Eyre Peninsula, Kangaroo to varying degrees in farming operations across Island and in the Broughton River basin (Figure 8.8), the region (data from data.daff.gov.au/anrdl/ and through the Mount Lofty and Flinders Ranges. metadata_files/pa_luav4g9abl07811a00.xml). Grazing Irrigated agriculture is mostly for viticulture and predominates in the northern arid river basins such wine production, the most important of which is as Lake Torrens, and Mambray concentrated in the Onkaparinga catchment. Coast (south of Lake Torrens), and the northern parts of the Broughton River basin. Several river basins (Wakefield, Gawler and Broughton) have 50% or more of their area occupied by dryland agriculture (Figure 8.7).

Figure 8.7 Land use in the South Australia Gulf region

Australian Water Resources Assessment 2012 11 South Australian Gulf

Figure 8.8 Land use distribution in the South Australian Gulf region

12 Australian Water Resources Assessment 2012 8.3.6 Population distribution A number of smaller coastal cities and towns are distributed along the edge of the Spencer Gulf and The South Australian Gulf region has a population of are driven by mining, agriculture and fisheries. greater than 1.4 million. Approximately 88% of the Beyond these smaller centres the remaining population is concentrated in greater Adelaide which population is sparsely distributed throughout the occupies the coastal plains along the eastern edge western and northern parts of the region. A number of the Gulf of St Vincent and extends up into the of remote Indigenous communities can be found Adelaide Hills (Figure 8.9). scatted throughout these parts.

Figure 8.9 Population density and distribution in the South Australian Gulf region

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8.3.7 Rainfall zones Moving south, the annual rainfall totals increase up to levels reaching over 600 mm in the southern tip of The region has a Mediterranean climate in the Eyre Peninsula and Kangaroo Island. southeast and a semi-arid climate to the north. For more information on this and other climate Rainfall mainly occurs in winter, though highly classifications, visit the Bureau of Meteorology’s (the variable contributor to rainfall in spring through to Bureau’s) climate website: www.bom.gov.au/jsp/ncc/ early autumn. Median rainfall varies strongly across climate_averages/climate-classifications/index.jsp the region, not exceeding 800 mm throughout (Figure 8.10). In the most northern part of the region average annual rainfall is limited to less than 200 mm.

Figure 8.10 Rainfall zones in the South Australian Gulf region

14 Australian Water Resources Assessment 2012 8.3.8 Rainfall deficit In the south of the region, dryland cropping and pasture for livestock are major forms of land use. The The rainfall deficit indicator, that is, rainfall minus farms strongly rely on April–October rainfall for their potential evapotranspiration, gives a general growing season. impression about which parts of the region are likely The city of Adelaide has some surface water storages to experience moisture deficits over the period of a to support the supply of water, but the general deficit year. The South Australian Gulf region has a general in this area means the city relies on water transferred pattern of substantial deficits in relation to this from the River Murray, particularly in summer, and indicator (Figure 8.11). since October 2011 from desalinated water. High deficits can be expected in large parts of the For more information on the rainfall and northern inland areas, which include a number of evapotranspiration data, see the Bureau’s maps ephemeral lakes. These are lakes which only get filled of average conditions: www.bom.gov.au/climate/ after major rainfall. No land cover other than grasses averages/maps.shtml and shrubs is present, resulting in low density stock farming.

Figure 8.11 Rainfall deficit distribution in the South Australian Gulf region

Australian Water Resources Assessment 2012 15 South Australian Gulf

8.4 Landscape water flows The soils refill again in the wetter May–July period. The monthly landscape water yield history for the This section presents analyses of the spatial and region shows a stable pattern of very low yield temporal variation of landscape water flows (rainfall, throughout the year. evapotranspiration and landscape water yield) The 2011–12 year was a relatively average year. across the South Australian Gulf region in 2011–12. Rainfall only exceeded the 90th percentile in National rainfall grids were generated using data the normally driest month of March, albeit only from a network of persistent, high-quality rainfall marginally. stations managed by the Bureau. Evapotranspiration and landscape water yields were derived using Similar to rainfall, evapotranspiration was the the landscape water balance component of the highest in March. The rainfall of February and March Australian Water Resources Assessment System contributed to higher than usual soil moisture, which (Van Dijk 2010). These methods and associated in turn was available again for evapotranspiration. output uncertainties are discussed in the Introduction Evapotranspiration for March was third highest on and addressed in more detail in the Technical record for the 1911–2012 period. Supplement. The landscape water yield for 2011–12 followed Figure 8.12 shows that the region has a seasonal the very narrow bounds of the historic pattern. A rainfall pattern with a predominantly wetter winter marginally higher landscape water yield was found and drier summer period. Evapotranspiration for March, although with no excessive volumes in generally exceeds rainfall from spring up to early absolute terms. summer, extracting the excess water from the soils.

Figure 8.12 Landscape water flows in 2011–12 compared with the long-term record (July 1911–June 2012) for the South Australian Gulf region

16 Australian Water Resources Assessment 2012 8.4.1 Rainfall Rainfall deciles for 2011–12 indicate average to above average rainfall for the entire region over the course Rainfall for the South Australian Gulf region for of the year (Figure 8.13b). The wetter south of the 2011–12 is estimated to be 331 mm. This is 10% region experienced predominantly average rainfall above the region’s long-term average (July 1911– with the exception of the far southern corner of Eyre June 2012) of 300 mm. Figure 8.13a shows that the Peninsula. In the centre and far north of the region, highest rainfall occurred along the southern coastal large areas of above average rainfall are present. As areas with annual totals locally exceeding 600 mm these areas are generally identified as arid, the above for 2011–12. The majority of the north had rainfall average areas experienced no substantially higher not exceeding 300 mm, except for the slopes of the absolute total annual rainfall. Flinders Ranges in the east.

Figure 8.13 Spatial distribution of (a) annual rainfall in 2011–12, and (b) their decile rankings over the 1911–2012 period for the South Australian Gulf region

Australian Water Resources Assessment 2012 17 South Australian Gulf

Rainfall variability in the recent past The graphs show a pattern of moderately high Figure 8.14a shows annual rainfall for the region variability for the region, which is linked to the highly from July 1980 onwards. Over this 32-year period the variable rainfall pattern in the arid north of the region. annual average was 305 mm, varying from 187 mm In Figure 8.14b, a pattern of decreasing rainfall in the (1982–83) to 477 mm (1992–93). Temporal variability winter period and increasing rainfall in the summer and seasonal patterns since 1980 are presented in period is found in the most recent years. Before this, Figure 8.14b. rainfall was noticeably higher in the winter period compared to the summer period.

Figure 8.14 Time-series of (a) annual rainfall, and (b) five-year retrospective moving averages for the summer (November– April) and winter (May–October) periods for the South Australian Gulf region

18 Australian Water Resources Assessment 2012 Recent trends in rainfall Figure 8.15a shows that trends are mostly rising, but Figure 8.15a presents the spatial distribution of the to an extent that is marginal. The significance map trends in annual rainfall for July 1980–June 2012. of Figure 8.15b confirms that the trends are of no These are derived from linear regression analyses on statistical importance. the time-series of each model grid cell. The statistical significance of the trends is provided in Figure 8.15b.

Figure 8.15 Spatial distribution of (a) trends in annual rainfall from 1980–2012, and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the South Australian Gulf region

Australian Water Resources Assessment 2012 19 South Australian Gulf

8.4.2 Evapotranspiration Evapotranspiration deciles for 2011–12 indicate average or above average totals across most of the Modelled annual evapotranspiration for the South region (Figure 8.16b). The pattern again reflects that Australian Gulf region for 2011–12 is estimated to of rainfall (Figure 8.13b), albeit with some minor be 306 mm. This is 7% above the region’s long-term differences. (July 1911–June 2012) average of 286 mm. The spatial Essentially, those areas that had above average distribution of annual evapotranspiration in 2011–12 rainfall also had above average evapotranspiration. (Figure 8.16a) is almost identical to that of rainfall Hence, most water was returned back to the (Figure 8.13a). In this region, evapotranspiration is atmosphere within a short period of time. mostly limited to the availability of water.

Figure 8.16 Spatial distribution of (a) modelled annual evapotranspiration in 2011–12, and (b) their decile rankings over the 1911–2012 period for the South Australian Gulf region

20 Australian Water Resources Assessment 2012 Evapotranspiration variability in the recent past The similarity between the rainfall data of Figure 8.17a shows annual evapotranspiration for the Figure 8.14 and the evapotranspiration data of region from July 1980 onwards. Over this 32-year Figure 8.17 is high. Evapotranspiration also shows period the annual evapotranspiration average was a narrowing of the difference between the summer 292 mm, varying from 191 mm (1982–83) to 447 mm and winter periods over the last few years. (1992–93). Figure 8.17b presents temporal variability and seasonal patterns since 1980.

Figure 8.17 Time-series of (a) annual evapotranspiration, and (b) five-year retrospective moving averages for the summer (November–April) and winter (May–October) periods for the South Australian Gulf region

Australian Water Resources Assessment 2012 21 South Australian Gulf

Recent trends in evapotranspiration Figure 8.18a shows that since 1980 trends throughout Figure 8.18a presents the spatial distribution of the the region are within the –2 to 2 mm/year range. trends in modelled annual evapotranspiration for As shown in Figure 8.18b, the trends are non- 1980–2012. These are derived from linear regression significant throughout the region. A major reason for analyses on the time-series of each model grid cell. this is that unlike in many other regions, the last two Figure 8.18b provides the statistical significance of years were not the highest on record for the 32-year the trends. period.

Figure 8.18 Spatial distribution of (a) trends in annual evapotranspiration from 1980–2012, and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the South Australian Gulf region

22 Australian Water Resources Assessment 2012 8.4.3 Landscape water yield The decile ranking map for 2011–12 (Figure 8.19b) shows very much above average landscape water Modelled landscape water yield for the South yield for the far north of the region. In absolute Australian Gulf region for 2011–12 is estimated to terms, however, these areas still had very low be 9 mm. This is 10% below the region’s long-term landscape water yield. In the far south some coastal (July 1911–June 2012) average of 10 mm. Figure areas are highlighted as very much below average 8.19a shows the spatial distribution of landscape landscape water yield; however, this is likely an water yield for 2011–12. Only in the far southeast and artefact of the model calculations, which has yet to on Kangaroo Island did some areas have landscape be further investigated. water yields exceeding 50 mm.

Figure 8.19 Spatial distribution of (a) modelled annual landscape water yield in 2011–12, and (b) their decile rankings over the 1911–2012 period for the South Australian Gulf region

Australian Water Resources Assessment 2012 23 South Australian Gulf

Landscape water yield variability The graphs show a weak pattern of cyclic behaviour in the recent past in the annual as well as summer and winter periods Figure 8.20a shows annual landscape water yield landscape water yield. Figure 8.20a shows that for the South Australian Gulf region from July 1980 landscape water yields for some years were around onwards. Over this 32-year period, annual landscape 5 mm or lower, which generally means that in the water yield was 10 mm, varying from 4 mm (1982– arid north of the region landscape water yield was 83) to 23 mm (1992–93). Temporal variability and close to zero for those years. seasonal patterns since 1980 are presented in Figure 8.20b.

Figure 8.20 Time-series of (a) annual landscape water yield and (b) five-year retrospective moving averages for the summer (November–April) and winter (May–October) periods for the South Australian Gulf region

24 Australian Water Resources Assessment 2012 Recent trends in landscape water yield Figure 8.21b, however, shows some strongly Figure 8.21a shows the spatial distribution of the significant rising trends occurring mainly in the trends in modelled annual landscape water yield for central west of the region and in the southern part 1980–2012. These are derived from linear regression of Yorke Peninsula. In absolute terms, though, the analyses on the time-series of each model grid cell. trends do not exceed 0.2 mm/year in the central The statistical significance of the trends is provided western area and 0.5 mm/year on Yorke Peninsula. in Figure 8.21b. The strongly significant falling trends on Kangaroo Island do not exceed –1 mm/year. Similar to rainfall and evapotranspiration, Figure 8.21a shows that since 1980 trends were within the –2 and 2 mm/year margins. With such low total annual landscape water yields involved, this is not surprising.

Figure 8.21 Spatial distribution of (a) trends in annual landscape water yield from 1980 to 2012 and (b) their statistical significance at 90% (weak) and 95% (strong) confidence levels for the South Australian Gulf region

Australian Water Resources Assessment 2012 25 South Australian Gulf

8.5 Surface water and 8.5.1 Rivers groundwater There are 11 river basins in the South Australian Gulf region, varying in size from 154–67,000 km2 This section examines surface water and (Figure 8.22). groundwater resources in the South Australian Gulf region in 2011–12. Rivers, wetlands and In the west and north, rivers are ephemeral and in storages are discussed to illustrate the state of the south east corner a few are perennial. There are the region’s surface water resources. The region’s only minor ephemeral streams in the northern half of watertable aquifers and salinity are described and the the region. groundwater status is illustrated by showing changes To the southeast of the region, short rivers drain into in groundwater levels at selected sites. the ocean. The perennial rivers flow off the slopes of the Mount Lofty Ranges into the Spencer Gulf. In the west, watercourses like the ephemeral Driver River flow from various low hills parallel to the coast on Eyre Peninsula. In the north, the Flinders Ranges supply most of the run-off from the east into Lake Torrens. Undulating land that averages less than 200 m above sea level, including the Andamooka Ranges, supplies the salt lake from the west.

Torrens River, Adelaide | Deqiang Pan, Dreamstime

26 Australian Water Resources Assessment 2012 Figure 8.22 Rivers and catchments in the South Australian Gulf region

Australian Water Resources Assessment 2012 27 South Australian Gulf

8.5.2 Streamflow volumes 8.5.3 Streamflow salinity

Figure 8.23 presents an analysis of flows at 14 Figure 8.24 presents an analysis of streamflow monitoring sites during 2011–12 relative to annual salinity for 2011–12 at 14 monitoring sites throughout flows for the period from July 1980–July 2012. the South Australian Gulf region. Monitoring sites Monitoring sites with relatively long records across with at least a five-year data record were selected six geographically representative rivers were for analysis. The results are presented as electrical selected (see the Technical Supplement for details). conductivity (EC, μS/cm at 25 ºC). This is a commonly The annual flows for 2011–12 are colour-coded used surrogate for the measurement of water according to the decile rank at each site over the salinity in Australia. Standard EC levels for different 1980–2012 period. applications, such as for drinking water or types of irrigation, are provided in the Technical Supplement. The flows are mostly average to above average and The median annual EC values are shown as coloured with some rivers showing very much below average circles. The size of the circle depicts the variability in annual flow for 2011–12. annual EC, shown as the coefficient of variation (CV), Very much above average flows were observed being the standard deviation divided by the mean. at two sites located on the in The median EC values for two monitoring sites in the the southeast and the in the far main rivers fall in the range 0–1,000 μS/cm (suitable southeast of the South Australian Gulf region. Of the for most irrigation uses). Most of the region’s rivers 15 monitoring sites, only one recorded above average and creeks fall outside this range (Figure 8.24). flows. This site was on the Hill River near Andrews in the Broughton River basin in the central southeast of Of the 14 monitoring sites, two had median EC the region. values between 500–1,000 μS/cm and a further two had values between 1,000–1,500 μS/cm. These Average flows occurred at seven monitoring sites are located on the rivers in the far southeast of the in the region. These are located on rivers in the region. Of the 14 sites, 71% had median EC values southeast and on the Rocky River on Kangaroo Island. above 2000 μS/cm. These are located on the rivers There was only one site where below average flows in the southeast, central southeast and at three sites were recorded. This was on the in on Kangaroo Island. The high salinity found in some the far southeast of the region. Very much below rivers is a reflection of natural conditions which are average flows were observed at three sites, which influenced by the dry climate, natural salt stores in are located on the rivers in the central-southeast and the landscape and naturally high saline groundwater on the in the southeast. intrusion which is suitable for most irrigation uses Flow deciles for the summer period (November (State of the Environment 2011). 2011–April 2012) are similar to total annual flows The CV is relatively low for the most of the for 2011–12 as shown in Figure 8.23. There are a monitoring sites in the region except for Tanunda few differences, such as the relatively higher flows Creek. The CV in EC is typically related to the observed in the summer period on the Onkaparinga variability in annual flow at the monitoring site. Of the River in the east of the region. 14 monitoring sites, 21% of them had a CV below 20%, and 71% of the sites had a CV between 20% and 60%. These were located on the rivers in the southeast, central south and on Kangaroo Island. The CV was above 60% in Tanunda Creek in the southeast of the region.

28 Australian Water Resources Assessment 2012 Figure 8.23 Average annual and summer period flow volumes of selected sites for 2011–12 and their decile rankings over the 1980–2012 period in the South Australian Gulf region

Australian Water Resources Assessment 2012 29 South Australian Gulf

Figure 8.24 Salinity as electrical conductivity and its associated coefficient of variation for 2011–12 in the South Australian Gulf region

30 Australian Water Resources Assessment 2012 8.5.4 Flooding The city of Adelaide is not fully dependent on storage water supply only. A large portion of the city’s water There were no major floods recorded for the South supply originates from transfers out of the River Australian Gulf region during the reporting year. Murray, which has recently been complemented by Minor flooding occurred only in local creeks in July desalinated water; however, the decrease in storage and September 2011 and in March 2012 (Figure 8.25). levels by 20% is not a favourable situation. This is reflected in stricter water conservation rules. 8.5.5 Storage systems More detailed information on the Adelaide water There are approximately 16 major publicly owned supply system is given in subsection 8.6, Water storages in the South Australian Gulf region with for cities and towns. Further information on the a total capacity in excess of 268 GL. The Bureau’s past and present volumes of the storage systems water storage website includes information on and the individual storages can be found on the approximately 74% of the region’s publicly owned Bureau’s water storage website: water.bom.gov.au/ storage capacities (as at August 2012) waterstorage/awris/ All of the storages in the Bureau’s water storage 8.5.6 Wetlands information for this region supply the city of Adelaide, adding up to a total accessible capacity of 197 GL. There are no Ramsar-listed, internationally important At the end of 2010–11, storage levels were at 135 wetlands in the South Australian Gulf region; GL (69% of total accessible capacity), but by the end however, there are a number of wetlands of national of 2011–12 this had dropped to 96 GL (49% of total importance mentioned in the Directory of Important accessible capacity). The location of all the systems Wetlands in Australia (www.environment.gov.au/ and associated storages are shown in Figure 8.26. water/topics/wetlands/database/diwa.html). The wetlands vary from coastal tidal flats to inland ephemeral lakes and large salt lakes (Figure 8.27). No detailed assessment on the inflows of selected wetlands has been performed for this region.

Australian Water Resources Assessment 2012 31 South Australian Gulf

Figure 8.25 Flood occurrence in 2011–12 for the South Australian Gulf region, with each dot representing a river level monitoring station and the colour of the dot representing the highest flood class measured

32 Australian Water Resources Assessment 2012 Figure 8.26 Storage systems in the South Australian Gulf region (information extracted from the Bureau’s water information website in August 2012)

Australian Water Resources Assessment 2012 33 South Australian Gulf

Figure 8.27 Location of important wetlands in the South Australian Gulf region

34 Australian Water Resources Assessment 2012 8.5.7 Hydrogeology 8.5.9 Groundwater management units

The hydrogeology of the South Australian Gulf The groundwater management units within the region can be partitioned into areas of surficial and region (Figure 8.30) are administrative boundaries underlying sediments, and areas of outcropping that are used to manage the extraction of fractured rock. groundwater through planning mechanisms. These areas are usually created to identify a significant Groundwater use in the region is largest in areas groundwater resource and to provide a boundary with surficial sediments and underlying aquifers. within which resource management effort can be Figure 8.28 shows major aquifer groups present at focused. Prescription is the legal mechanism for the watertable. Aquifer groups that provide potential implementing a water resource management regime for groundwater extraction (as labelled in Figure 8.2) in South Australia. A prescribed water resource is are: managed through an allocation and licensing system • lower mid-Tertiary aquifer ; where the emphasis is on groundwater. These areas (porous media— unconsolidated) are known as water resources prescribed areas and • upper Tertiary aquifer prescribed wells areas within South Australia. (porous media— unconsolidated); and Groundwater management units are found in areas • upper Tertiary/Quaternary aquifer with significant fresh groundwater resources. These (porous media—unconsolidated). are the surficial sediments and the underlying The sediments of the Great Artesian Basin are Quaternary and Tertiary aquifers. The fractured present along the northern boundary of the region rock systems typically offer restricted low volume but are not dominant for water provision. groundwater resources; however, there are some parts of this region with a greater density of fractures 8.5.8 Water table salinity and more substantial groundwater resources. Typically, groundwater use is high in prescribed wells Figure 8.29 shows the classification of watertable areas such as McLaren Vale, the northern and central aquifers as fresh (total dissolved solids [TDS] < 3,000 Adelaide Plains, and the southern basins. mg/L) or saline (TDS ≥ 3,000 mg/L). As shown, most parts of the region are considered to have saline groundwater that is usually not suitable for irrigation. Non-saline groundwater occurs in the east of the region and in particular around the Adelaide area.

Australian Water Resources Assessment 2012 35 South Australian Gulf

Figure 8.28 Watertable aquifer groups in the South Australian Gulf region; data extracted from the Groundwater Cartography of the Australian Hydrological Geospatial Fabric (Bureau of Meteorology 2012)

36 Australian Water Resources Assessment 2012 Figure 8.29 Watertable salinity classes in the South Australian Gulf region; data extracted from the Groundwater Cartography of the Australian Hydrological Geospatial Fabric (Bureau of Meteorology 2013)

Australian Water Resources Assessment 2012 37 South Australian Gulf

Figure 8.30 Groundwater management units in the South Australian Gulf region; data extracted from the National Groundwater Information System (Bureau of Meteorology 2013)

38 Australian Water Resources Assessment 2012 8.5.10 Status of selected aquifers Adelaide Plain aquifers Figure 8.31 illustrates the spatial and temporal grid The status of groundwater levels is assessed for the analyses of trends in groundwater levels of the Adelaide Plains and McLaren Vale aquifers which Adelaide watertable over the period 2007–08 to are major groundwater resources for the region. 2011–12. Trends in groundwater levels were analysed These aquifers are associated with three of the in data-rich areas only. As shown in Figure 8.31, most important groundwater management units in the north of the aquifer groundwater levels are (prescribed well areas) shown in Figure 8.30. The mostly rising. This reflects the increased groundwater assessment of groundwater levels evaluates trends recharge due to the recent high rainfall. in groundwater levels over the 2007–08 to 2011–12 period. Selected bores 1 and 2 show variability in groundwater levels but no significant trend over the period. The trends in groundwater levels are investigated Peaks in water levels in these two bores represent using a 5 km x 5 km grid cell across data rich areas. groundwater response to infrequent recharge events. This scale reflects the size of the selected aquifers in In contrast, Bore 3 shows stable levels until 2010. All the region. The linear trend in groundwater levels for bores show an increase in groundwater level after a grid cell is assessed as: 2010 indicating recharge to groundwater during the • decreasing (where more than 60% of the recent high rainfall period. bores have a negative trend in levels lower Figure 8.32 illustrates the spatial and temporal than –0.1 m/year); grid analyses of trends in groundwater levels for • stable (where the trend is lower than 0.1 m/year the Tertiary aquifer T1 over the period 2007–08 to and higher than –0.1 m/year for more than 60% 2011–12. The trend analysis for the south of the of the bores); aquifer indicates that groundwater levels for the past • increasing (where more than 60% of the bores five years are either declining or variable. This is most have a positive trend in levels higher than likely in response to groundwater extraction in the 0.1 m/year); and southern area. • variable (where there is no dominant trend in groundwater levels amongst the bores within a The selected hydrographs 4–6 indicate that variability grid cell). in levels within a year is much larger than the inter- annual trend in levels. This illustrates the seasonal Example bore hydrographs are presented for each cycles of pumping and recovery of groundwater aquifer over the entire record length and trends are levels at the end of pumping season. All selected discussed with a focus on the 2007–08 to 2011–12 bores show a declining trend for the period 2007–08 period. The selected bore hydrographs represent to 2009–10 period and various degrees of recovery mostly bores with high data density that were used of groundwater levels, and therefore recharge, in the 2010 Assessment. Aquifers considered: associated with higher rainfall since 2010. • Adelaide Plains watertable Figure 8.33 illustrates the spatial and temporal grid • Adelaide Plains Tertiary aquifer 1 (T1) analyses of trends in groundwater levels for the • Adelaide Plains Tertiary aquifer 2 (T2) Tertiary aquifer T2 over the period 2007–08 to • McLaren Vale watertable 2011–12. The analysis for T2 aquifer is focused in the • Willunga north of the aquifer, and shows that groundwater levels for the past five years are either increasing • Maslin. or variable, similary to the watertable aquifer. All selected bores show declining trends for the period 2007–08 to 2009–10 and some degree of recovery thereafter.

Australian Water Resources Assessment 2012 39 South Australian Gulf

Figure 8.31 Spatial distribution of trends in groundwater levels for the Adelaide Plains watertable in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

40 Australian Water Resources Assessment 2012 Figure 8.32 Spatial distribution of trends in groundwater levels for the Adelaide Plains T1 aquifer in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

Australian Water Resources Assessment 2012 41 South Australian Gulf

Figure 8.33 Spatial distribution of trends in groundwater levels for the Adelaide Plains T2 aquifer in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

42 Australian Water Resources Assessment 2012 McLaren Vale aquifers The selected bores 13–15 show continuously declining Figure 8.34 illustrates the spatial and temporal trends levels since the start of the records, with annual in groundwater levels of the McLaren Vale watertable fluctuations in groundwater levels that correspond to over the period 2007–08 to 2011–12. Grid analyses seasonal cycles of pumping and recovery. of trends in groundwater levels were carried out Figure 8.36 shows the grid analyses of trends in data-rich areas only where three or more bores in groundwater levels within the Maslin aquifer, were present in a grid cell. As shown in Figure 8.34, indicating no prevalent trend over the period groundwater levels are consistently stable. 2007–08 to 2011–12; however, no grid cells with The selected bores 10–12 have annual fluctuations an overall declining trend are present. This aquifer in water levels that are most likely caused by becomes unconfined in the northeast; therefore seasonal groundwater recharge to the watertable. the groundwater level trends are likely to reflect the Hydrographs for these bores illustrate long- term recent groundwater recharge episodes due to high relatively stable trends in water levels and, in rainfall. particular, no major recharge event since 2010. Bores 16, 17 and 18 located at the eastern and Figure 8.35 shows the grid analyses of trends in southern ends of the Maslin Sands aquifer have groundwater levels within the underlying Willunga stable water levels for the period 2007–08 to 2011–12 aquifer, illustrating stable or declining levels for the with no major recharge episode post 2010. Bore 17, period 2007–08 to 2011–12.This is a highly utilised located at the western end of the aquifer, shows aquifer and therefore the declining trends are most annual fluctuations in water level that may be due to likely driven by groundwater extraction. pumping from a nearby bore.

Australian Water Resources Assessment 2012 43 South Australian Gulf

Figure 8.34 Spatial distribution of trends in groundwater levels for the McLaren Vale watertable in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

44 Australian Water Resources Assessment 2012 Figure 8.35 Spatial distribution of trends in groundwater levels for the Port Willunga aquifer in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

Australian Water Resources Assessment 2012 45 South Australian Gulf

Figure 8.36 Spatial distribution of trends in groundwater levels for the Maslin Sands aquifer in the South Australian Gulf region for 2007–08 to 2011–12, with selected hydrographs showing groundwater levels

46 Australian Water Resources Assessment 2012 8.6 Water for cities and towns The major urban centres of the region (populations over 10,000 people) are also summarised in Table 8.3. This section examines the urban water situation This table provides information on the population, in the South Australian Gulf region in 2011–12. The surrounding river basins and significant water large urban centres in the region, their water supply storages for each of the major centres. systems and storage situations are briefly described. Whyalla, with a population of just under 22,000, The main urbanised area, Adelaide, is discussed in is the region’s second most populous city. It is a more detail in subsection 8.6.3, including the history seaport located on the northeast coast of the Eyre of water restrictions over recent years. Peninsula. The town is strongly influenced by the mining industry. 8.6.1 Urban centres Port Lincoln is the third major town in the South Adelaide is the largest city in the South Australian Australia Gulf region and has a population of just over Gulf region and has more than 1.1 million residents. 14,000. It is a seaside town on Boston Bay at the It is located north of the Fleurieu Peninsula, on the southern extremity of the Eyre Peninsula. It is the Adelaide Plains between the Gulf of St Vincent and largest town in the west of the region, and is located the low-lying Mount Lofty Ranges which surround approximately 650 km from Adelaide. the city. Adelaide stretches 20 km from the coast to Port Augusta has a population of just fewer than the foothills, and 90 km from Gawler at its northern 14,000 and is the region’s fifth most populous town. extent to Sellicks Beach in the south. It is a seaport and railway junction at the northern tip Beyond Adelaide the region has four major population of the Spencer Gulf. centres: Whyalla, Port Lincoln, Port Augusta and The population of Port Pirie is 13,800. It is also a Port Pirie. These urban centres, along with Adelaide seaport on the east coast of the Spencer Gulf, about and other regional towns in conjunction with their 225 km north of Adelaide. population ranges, are shown in Figure 8.37.

Table 8.3 Cities and their water supply sources in the South Australian Gulf region

City Population1 River basin Major supply sources Adelaide 1,104,000 Gawler, Torrens, Myponga, Barossa, Little Para, Kangaroo Onkaparinga, Myponga Creek, Mount Bold, Happy Valley, Hope and Fleurieu Peninsula Valley, Warren, Millbrook and South Para storages Whyalla 21,700 Spencer Gulf River Murray (Morgan–Whyalla pipeline) Port Lincoln 14,100 Eyre Peninsula Groundwater (Southern Basins) River Murray (Morgan–Whyalla pipeline) Port Pirie 13,800 Mambray Coast and Baroota storage, River Murray (Morgan– Broughton River Whyalla pipeline) Port Augusta 13,500 Mambray Coast River Murray (Morgan–Whyalla pipeline)

1 Australian Bureau of Statistics (2011b)

Australian Water Resources Assessment 2012 47 South Australian Gulf

Figure 8.37 Population range of urban centres in the South Australian Gulf region

48 Australian Water Resources Assessment 2012 8.6.2 Sources of water supply Water supply system Historically, the provision of a reliable and secure While the regions’s surface water storages play an water supply to Adelaide has been a challenge important role in the provision of its water supplies, because of its highly variable rainfall; however, the its relatively low rainfall and long, dry summers construction of a series of major pipelines supplying have seen a growth in its dependence on diversions water from the River Murray and construction of a from the River Murray to meet its demands. South desalination plant have served to further ensure a Australia holds an 1,850 GL-per-year entitlement to reliable water supply for Adelaide. flows in the River Murray and during good rainfall years is entitled to extract an additional 3 GL per day Key components of the Adelaide water supply as dilution flows. system include the Mannum–Adelaide and Murray Bridge–Onkaparinga pipelines, ten major storages Flows extracted from the Murray are distributed totalling 197 GL in capacity, seven water treatment throughout the region by five bulk water transfer plants and twelve wastewater treatment plants. In pipelines totalling over 650 km in length. addition, a number of privately operated bore fields The Mannum–Adelaide and the Murray Bridge– supply groundwater primarily for agricultural uses. Onkaparinga pipelines supply the city of Adelaide Some treated water is exported to adjacent regions while the Swan Reach–Stockwell pipeline supplies for urban consumption. water to townships (and farms) north of Adelaide and The Mannum–Adelaide pipeline was the first of along its route. the pipelines built to deliver River Murray water to The Morgan–Whyalla pipeline supplies many of Adelaide. It supplies water to the Anstey Hill water the regions northern population centres and rural treatment plant and to a number of storages. communities, including those of Whyalla, and Port The Murray Bridge–Onkaparinga pipeline was Augusta to Woomera. At a length of 379 km, it is completed in 1973 and supplies water to the Summit the longest of the five major pipelines in the region. Storage water treatment plant as well as releasing Communities in the upper southeast of the region water into the Onkaparinga River for collection and are supplied via the Tailem Bend–Keith pipeline. treatment downstream. Figure 8.38 shows the major pipelines and storages in use for urban water supply. Development of the Port Stanvac desalination plant was staged by constructing two 50 GL per year In addition to imported and surface water storages, capacity plants. The first plant started production in the region relies heavily on groundwater, recycled October 2011 and the second during late 2012. Water water and harvested storm and rainwater to supply from the desalination plant is mixed with treated its urban demands. In particular, South Australia has surface water from the Happy Valley water treatment been a national leader in the use of recycled and plant and discharged directly into Adelaide’s stormwater. distribution system. 8.6.3 Adelaide SA Water operates a number of recycled water and stormwater harvesting schemes. It also strongly The South Australia Water Corporation (SA Water) is promotes individual use of rainwater across the the South Australian Government-owned statutory region. A number of recycled water schemes that body that owns and manages Adelaide’s water supply treated effluent for agricultural and municipal supply systems, recycled water systems and irrigation and residential use operate within the wastewater services. SA Water controls surface greater Adelaide area. Several community or privately water diversions, operates water treatment plants operated recycling schemes supply to viticulture and and maintains Adelaide’s reticulation system. municipal applications. It supplies customers in the greater Adelaide area which includes the city of Adelaide as well as the surrounding suburbs, stretching over the Gawler, Torrens, Onkaparinga and Myponga river basins.

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Figure 8.38 Water supply systems in the South Australian Gulf region

50 Australian Water Resources Assessment 2012 Storage volumes Bold serves the southern Adelaide suburbs from the The Mount Bold, South Para, Kangaroo Creek and Torrens River to the Onkaparinga River. Water from Myponga storages constitute 69% of the total Myponga is distributed along the coast from the Adelaide system storage. South Para serves the Onkaparinga River to Normanville. The accessible Northern Adelaide Plains. Kangaroo Creek is used volumes of these major storages are shown to supply water to the northern Adelaide suburbs individually in Figure 8.39. from Port Adelaide to the Torrens River while Mount

Mount Bold

South Para

Kangaroo Creek

Myponga

Figure 8.39 Variation in the amount of water held in storage over recent years (light blue) and over 2011–12 (dark blue) for Mount Bold, South Para, Kangaroo Creek and Myponga storages, as well as total accessible storage capacity (dashed line)

Australian Water Resources Assessment 2012 51 South Australian Gulf

Mount Bold is the largest storage, with a capacity of Water restrictions 46 GL, and it contributes approximately 20% of the Water restriction in Adelaide and in most of the total storage capacity. region are set by the State Government and enforced The large annual fluctuation of the accessible storage by SA Water. Restriction triggers are not solely shown in these figures illustrates the highly variable based on the total available water in storage. Water nature of Adelaide’s surface water resources. The restrictions in Adelaide are instead dependent on figures highlight the general trend of filling during flows from the Mount Lofty Ranges and also on July–October and their drawdown across the drier conditions in the Murray–Darling Basin, including summer period. volumes in the Hume and Dartmouth storages. Extractions from the River Murray are highly Restrictions applied to Adelaide outdoor water dependent on the inflows to storages from their consumption are shown against combined storage surrounding catchments. Extractions can range from volumes of Mount Bold, South Para, Kangaroo Creek 40% of the total water sourced in high rainfall years and Myponga in Figure 8.40. to 90% in years of very low rainfall. In the early 2000s, local storages, catchments and the River Murray were stressed as a result of drought conditions within the region and the Murray – Darling Basin. This saw Level 2 water restrictions introduced in July 2003 for four months. Permanent water conservation measures (PWCM) were introduced in October 2003, promoting long-term water conservation.

Figure 8.40 Urban water restriction levels across Adelaide since 2001 shown against the combined accessible water volume of Mount Bold, South Para, Kangaroo Creek and Myponga storages

52 Australian Water Resources Assessment 2012 Enhanced level 2 restrictions were introduced in Sources of water obtained October 2006, after a record dry winter and record Figure 8.41 shows the total volume of water sourced low inflows into the River Murray. They were quickly from surface water, recycled and desalination water replaced in January 2007 by Level 3 restrictions for supply to Adelaide (National Water Commission and average annual residential water use decreased 2012). Demand management and water conservation from 235 to 180 kL/property in 2006–07 to 2010–11 measures have seen a continuing decline in the total respectively. water sourced by SA Water. An easing in water restriction levels in 2011–12 has Between 2006–07 and 2011–12, the highest volume been in part attributed to a rise in the average annual of total water sourced was 181 GL in 2006–07, which domestic water consumption of Adelaide, increasing was a very dry and hot year. Over the following three to 195 kL/property (National Water Commission years, the volume of water sourced was lower and 2012).The South Australian Government imposed a constant as a result of demand management through temporary cessation on all outdoor watering in July water restrictions. 2007 which was extended through to August and September due to low winter flows. In October 2007, In 2011–12, recycled water comprised 3% of the Adelaide residents were permitted to water for three total water sourced for Adelaide. A further 3% was hours per week; this was increased to five hours and sourced from desalinated water. For the remaining then seven hours in April and May 2010 respectively. years shown in Figure 8.41, approximately 15% of the total water sourced was recycled water. Permanent water wise measures (WWM) were introduced on 1 December 2010 to cement water conservation across the region and to include measures to manage domestic and commercial water use.

Figure 8.41 Total urban water sourced for Adelaide from 2006–07 to 2011–12

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Categories of water delivered The Level 2 and Level 3 restrictions introduced in Figure 8.42 shows the total volume of water 2006–07 reduced annual residential consumption to delivered to residential, commercial, municipal, an average of 93 GL over the period 2007–08 to industrial and other consumers in Adelaide from 2010–11. The average commercial, municipal and 2006–07 to 2011–12. Water supply data of the last industrial water consumption in Adelaide during six years has been obtained from the National 2006–07 to 2011–12 was about 28 GL, with a Water Commission’s National Performance Reports maximum of more than 35 GL in 2006–07. By (National Water Commission 2013). 2011–12, consumption by the commercial, municipal and industrial sectors fell to 26 GL with the lowest Water supply has steadily decreased from 2006–07 at 16 GL in 2009–10, almost half of the 2006–07 to 2010–11. The consumption of water increased consumption. in 2011–12 due to the lower water restrictions and above average rainfall in the region. Residential water Based on the data obtained from the National use constitutes between 66% and 75% of Adelaide’s Performance Reports, the average water supply total water consumption. The maximum residential per property for residential use in Adelaide from water use in Adelaide was during the year 2006–07 2006–07 to 2011–12 was estimated to be 195 kL. The when more than 115 GL were supplied for residential maximum annual residential water use per property use. As discussed above, water restrictions and was 235 kL in 2006–07 and the minimum was conservation measures subsequently had a marked 180 kL in 2010–11. influence on residential water use.

Figure 8.42 Categories of water delivered to Adelaide from 2006–07 to 2011–12

54 Australian Water Resources Assessment 2012 8.7 Water for agriculture 8.7.1 Soil moisture

This section describes the water situation for Since model estimates of soil moisture storage agriculture in the South Australian Gulf region during volumes are based on a simple conceptual the 2011–12 year compared with the past. Modelled representation of soil water storage and transfer soil moisture conditions are presented and important processes averaged over a 5 km x 5 km grid cell, irrigation areas are identified. The McLaren Vale they are not suitable for comparison with locally Irrigation Area is described in more detail. measured soil moisture volumes. This analysis therefore presents a relative comparison only, identifying how modelled soil moisture volumes of 2011–12 relate to modelled soil moisture volumes of the 1911–2012 period, expressed in decile rankings. Except for a narrow strip in the northern pastoral lands which had high above average soil moisture conditions, the South Australian Gulf region experienced average conditions (Figure 8.43). This follows the rainfall decile ranking during 2011–12 in the region. The similarity is more distinct for the northern and southern parts of the region. Some irrigated lands of the southern region experienced below to very much below average soil moisture conditions (Figure 8.43). Decile ranking of the changes in soil moisture averaged over the whole region during 2011–12 year indicates marginally above average conditions that rose in March due to historically high rainfall events, and continued during the autumn period (Figure 8.44).

Figure 8.43 Deciles rankings of annual average soil Figure 8.44 Decile ranking of the monthly soil moisture moisture for 2011–12 with respect to the conditions during the 2011–12 period in the 1911–2012 period for the South Australian South Australia Gulf region Gulf region

Australian Water Resources Assessment 2012 55 South Australian Gulf

8.7.2 Irrigation water 8.7.4 McLaren Vale prescribed wells area

A comparison of annual irrigation water use in parts The McLaren Vale prescribed wells area is located of the region for the period between 2005–06 and within the Onkaparinga catchment, 35 km south 2010–11 is shown by natural resource management of Adelaide within the boundaries of the Western (NRM) regions in Figure 8.45. Figure 8.46 shows the Mount Lofty Ranges prescribed area, and covers an variation in annual water use between the two NRM area of 320 km2. regions in the South Australian Gulf region during By regulation in 1998, all existing and future wells 2010–11 year. within the area were declared to be prescribed wells. Data for the 2011–12 year was not available at the Prescription is the legal mechanism for implementing time of preparation of this report. a water resource management regime in South Australia. A prescribed water resource is managed The McLaren Vale prescribed wells area in the through an allocation and licensing system. Onkaparinga catchment is described in the following section as an example of irrigated agriculture water The area was formed after amalgamating the use in the region. Willunga Basin prescribed wells area and the Upper Willunga catchment moratorium area in 2000. The 8.7.3 Irrigation areas climate of the area is Mediterranean, with cool, wet winters and hot, dry summers. Annual rainfall varies Dryland agriculture is the main agricultural activity in from around 400 mm to around 900 mm. Irrigated the South Australian Gulf region apart from grazing viticulture accounts for more than 85% of the pasture. Viticulture and wine grape production is the irrigation in the region. Orchards and other irrigated main irrigated agriculture mostly in the Onkaparinga crops account for the remainder. catchment (Figure 8.47). Water for these enterprises is sourced from the Mount Lofty Ranges and River There are no large surface water inflows or storages Murray diversions. Mount Bold on the Onkaparinga in the McLaren Vale prescribed wells area. Around River is the largest storage in the region with an 75% of water used for irrigation in the McLaren Vale accessible storage capacity of 46 GL. prescribed wells area is sourced from groundwater. Groundwater occurs in four major aquifers: the In most years, inflows to storage are supplemented Quaternary aquifer, Port Willunga Formation aquifer, by water pumped from the River Murray via a Maslin Sands aquifer and Fractured Rock aquifer. pipeline from Murray Bridge. The majority of irrigated water use occurs in the south-eastern areas where viticulture is concentrated. The McLaren Vale prescribed wells area is described in more detail in section 8.7.4 below.

Figure 8.45 Total annual irrigation water use for 2005–06 to 2010–11 for natural resource management regions in the South Australian Gulf region (ABS 2006–2010; 2011a)

56 Australian Water Resources Assessment 2012 Figure 8.46 Annual irrigation water use per natural resource management region for 2010–11 (ABS 2011a)

Australian Water Resources Assessment 2012 57 South Australian Gulf

Figure 8.47 Irrigation areas in the South Australian Gulf region

58 Australian Water Resources Assessment 2012 The high cost of groundwater has encouraged the Local hydrogeology development of alternative water sources such as For the purpose of this report, the McLaren Vale mains water and secondary treated water from Irrigation Area was selected as an example for the the Christies Beach wastewater treatment plant discussion of groundwater use in an irrigation area in (Government of South Australia 2000). the South Australian Gulf region. There is an extraction limit of 6,600 ML from The aquifer system in the McLaren Vale prescribed groundwater. Most of the water is extracted from the wells area (Figure 8.48) is complex but can be Port Willunga Formation aquifer. Average allocation in grouped into four aquifers listed from top to bottom: McLaren Vale is 1.5 ML/ha for vines and 2.8 ML/ha the Quaternary sediments, Willunga Formation, for other crops. Maslin Sands and fractured basement rock. These Metered groundwater extractions in the McLaren aquifers are interconnected and as such, withdrawals Vale prescribed wells area for 2010–11 totalled from one aquifer will impact other aquifers. 2,529 ML, 27% less than the previous year mostly Furthermore, the aquifers are not all present at all because of above average rainfall in the region near locations in McLaren Vale. Mount Bold (Department for Water 2011). Data for the 2011–12 year was not available at the time of preparation of this report.

Figure 8.48 The McLaren Vale Prescribed Wells Area showing the location of groundwater bore sites and rain gauge

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The Willunga aquifer supplies 64% of groundwater Fluctuations in the shallow groundwater levels were extracted for irrigation, with the Maslin Sands and evaluated for the watertable aquifer at five selected fractured basement rock aquifers supplying 20% and sites using data between 1990 and 2012 (Figure 8.49). 16% respectively (Australian Bureau of Agricultural In Figure 8.49 fluctuation in groundwater levels are and Resource Economics and Sciences 2003). compared to the local monthly rainfall trend (location of rain gauge shown in Figure 8.48). Periods in which The Quaternary aquifer is generally shallow and of the cumulative rainfall residual mass curve rises poor quality; however, it plays an important role in indicate wetter than average conditions. Periods with supporting groundwater-dependent ecosystems a falling trend indicate drier than average conditions. such as Aldinga Scrub and by providing base flow Panel b in Figure 8.49 shows a wetter than average to creeks and streams (Department of Water, Land period up to 1994, followed by average rainfall and Biodiversity Conservation 2007).The Willunga conditions until 2006, then by a drier than average aquifer is the most utilised groundwater resource in period up to 2009, and thereafter by average rainfall. McLaren Vale prescribed wells area and is comprised of sand and limestone units. The Maslin Sands The figure illustrates that overall the groundwater aquifer overlies the Fractured Rock aquifer. The response to trends in rainfall is prominent. It also aquifer is unconfined in the northeast of the area. shows that groundwater recharge in the watertable is Like the Willunga aquifer, recharge occurs via direct driven by seasonal cycles in rainfall. All wells, except rainfall infiltration in unconfined areas as well as from for one, show a decline in water level after 2006 and streams and inflow from surrounding fractured rocks. a minor recovery post 2009. This was as a result of below average rainfall conditions in the region from In the McLaren Vale prescribed wells area, localised 2006 to 2009 followed by averaged rainfall (panel b in cones of depression in the groundwater level due Figure 8.49). The pattern and magnitude of change in to groundwater pumping have been identified as a groundwater level is also influenced by the change in potential problem, particularly for saline seawater the pattern of extraction across the area. intrusion (Martin 1998; Martin and Hodgkin 2005). Stewart (2006) reported higher salinities between Groundwater level McLaren Vale and Blewitt Springs than in the Figure 8.50 shows ranges of groundwater depth remainder of the aquifer. This area coincides with from bores located in the three aquifers in the a deflection in the potentiometric surface for the McLaren Vale Irrigation Area, and the ranking of aquifer. 2011–12 median groundwater levels compared to Groundwater quality overview annual median groundwater levels in the last 21 years (1990–2011). Groundwater salinity increases towards the coast in the Port Willunga formation aquifer. This increase As shown in Figure 8.50, typically groundwater levels of salinity down the hydraulic gradient suggests in the watertable aquifer vary from very shallow that recharge to this aquifer is limited along the 0–1 m from the surface to greater than 10 m from groundwater flow path. The salinity of the Maslin the surface. Median groundwater depths in 2011–12 Sands aquifer is similar to that of the Port Willunga are typically below the long-term average east of Formation aquifer. The salinity in the Fractured Rock McLaren Vale town and are generally above the long- aquifer is variable, but generally fresh. term average elsewhere.

Influences on shallow groundwater Groundwater levels in the Willunga aquifer in 2011–12 are over all deeper than 10 m below the surface There is often a very strong relationship observed (Figure 8.51). The recorded groundwater levels are in shallow aquifer systems between changes in mostly below the long-term average of the past 21 groundwater levels and rainfall, which occur as years. a result of rapid recharge to these systems from rainfall (Department of Water, Land and Biodiversity Conservation 2007). Therefore, years of above average rainfall will result in rising groundwater levels, while years of below average rainfall will result in declining groundwater levels.

60 Australian Water Resources Assessment 2012 In the Maslin Sands (Figure 8.52), groundwater levels Groundwater salinity in 2011–12 were also generally deep (>5 m below At the time of writing, suitable quality controlled the surface). Overall, groundwater levels in the area and assured time-series data on groundwater increased concurrent with the expansion of irrigated salinity were not available from the Australian land. Towards the coast, groundwater levels are Water Resources Information System (Bureau of below the average for the last 21 years. Meteorology 2011a). Therefore, groundwater salinity status of the McLaren Vale Irrigation Area has not been analysed.

Figure 8.49 (a) Groundwater levels between 1990 and 2012 of the watertable aquifer at five bore sites in the McLaren Vale Irrigation Area, compared with (b) rainfall residuals, and (c) daily rainfall at Willunga

Australian Water Resources Assessment 2012 61 South Australian Gulf

Figure 8.50 (a) Median groundwater depth below surface, and (b) groundwater level deciles in 2011–12 compared to the 1990–2012 reference period for the McLaren Vale watertable aquifer

62 Australian Water Resources Assessment 2012 Figure 8.51 (a) Median groundwater depth below surface, and (b) groundwater levels deciles in 2011–12 compared to the 1990–2012 reference period for the Willunga aquifer

Australian Water Resources Assessment 2012 63 South Australian Gulf

Figure 8.52 (a) Median groundwater depth below surface, and (b) groundwater levels deciles in 2011–12 compared to the 1990–2012 reference period for the Maslin Sands aquifer

64 Australian Water Resources Assessment 2012